Microsoft has been in that market for much longer and yet cannot get traction. One of the biggest things for me with both Windows Mobile and Ubuntu was the lack of actual phones I could buy through my carrier. If they're not available to me I cannot buy them, if I cannot buy them, neither can anyone else on my carrier who would love to, and I'm sure there's plenty of people frustrated with Android and iOS alike. Shame we cannot have a true Linux OS.
Edit: To be fair I saw some phones from Microsoft on my carrier, but their battery life that was advertised was terrible, and there were few of them. If there had been 2 ~ 3 phones and new ones every few months, now we're talking... Ah well. I would prefer to see a Linux phone but I wouldn't mind buying a Windows one if they didn't feel like they could be abandoned like a couple of Microsoft's products wind up.